The capacity of a magazine on an automatic weapon places a constraint on the number of rounds which may be fired between reloading operations. Magazines for hand-carried weapons have generally been limited by the weight of the magazine and its contained rounds to spring-loaded magazines having a capacity of a few dozen rounds.
Although belt-fed or linked rounds provide the potential for a large magazine capacity, the weight of conventional ammunition and their containers has limited belt and linked ammunition feed to stationary or mobile applications.
The recent trend to smaller and lighter ammunition such as, for example, 5.56 mm cartridges, permits a single operator to carry enough ammunition mounted on the weapon to make belt-type feed very attractive if it could be readily loaded by any upright walking operator carrying the weapon. Since one of the operator's hands is occupied supporting the weapon, any reloading operation must be accomplished by his single remaining hand. Furthermore, besides mounting the ammunition, it should be made ready to firing preferably by the mere act of mounting the ammunition on the weapon.